| /* Copyright (c) 2016 John Fastabend <john.r.fastabend@intel.com> |
| * |
| * This program is free software; you can redistribute it and/or |
| * modify it under the terms of version 2 of the GNU General Public |
| * License as published by the Free Software Foundation. |
| * |
| * This program is distributed in the hope that it will be useful, but |
| * WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| * General Public License for more details. |
| */ |
| #define KBUILD_MODNAME "foo" |
| #include <uapi/linux/bpf.h> |
| #include <linux/in.h> |
| #include <linux/if_ether.h> |
| #include <linux/if_packet.h> |
| #include <linux/if_vlan.h> |
| #include <linux/ip.h> |
| #include <linux/ipv6.h> |
| #include "bpf_helpers.h" |
| |
| struct { |
| __uint(type, BPF_MAP_TYPE_ARRAY); |
| __type(key, int); |
| __type(value, int); |
| __uint(max_entries, 1); |
| } tx_port SEC(".maps"); |
| |
| /* Count RX packets, as XDP bpf_prog doesn't get direct TX-success |
| * feedback. Redirect TX errors can be caught via a tracepoint. |
| */ |
| struct { |
| __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY); |
| __type(key, u32); |
| __type(value, long); |
| __uint(max_entries, 1); |
| } rxcnt SEC(".maps"); |
| |
| static void swap_src_dst_mac(void *data) |
| { |
| unsigned short *p = data; |
| unsigned short dst[3]; |
| |
| dst[0] = p[0]; |
| dst[1] = p[1]; |
| dst[2] = p[2]; |
| p[0] = p[3]; |
| p[1] = p[4]; |
| p[2] = p[5]; |
| p[3] = dst[0]; |
| p[4] = dst[1]; |
| p[5] = dst[2]; |
| } |
| |
| SEC("xdp_redirect") |
| int xdp_redirect_prog(struct xdp_md *ctx) |
| { |
| void *data_end = (void *)(long)ctx->data_end; |
| void *data = (void *)(long)ctx->data; |
| struct ethhdr *eth = data; |
| int rc = XDP_DROP; |
| int *ifindex, port = 0; |
| long *value; |
| u32 key = 0; |
| u64 nh_off; |
| |
| nh_off = sizeof(*eth); |
| if (data + nh_off > data_end) |
| return rc; |
| |
| ifindex = bpf_map_lookup_elem(&tx_port, &port); |
| if (!ifindex) |
| return rc; |
| |
| value = bpf_map_lookup_elem(&rxcnt, &key); |
| if (value) |
| *value += 1; |
| |
| swap_src_dst_mac(data); |
| return bpf_redirect(*ifindex, 0); |
| } |
| |
| /* Redirect require an XDP bpf_prog loaded on the TX device */ |
| SEC("xdp_redirect_dummy") |
| int xdp_redirect_dummy_prog(struct xdp_md *ctx) |
| { |
| return XDP_PASS; |
| } |
| |
| char _license[] SEC("license") = "GPL"; |